Gas props on nitro rigger

[Jim Allen]

"The Brown and sharp is out of my price range."

Don't buy anything made by Brown & Sharp. Buy one of the Chinese copies. With a little tune up time, you can make this work as good as a B & S, especially for what we are doing in our toy motors. The reason a dividing head is preferred; the exact position necessary is determined with a tappered pin in a hole, not by reading a vernier scale. If you decide to use this, I will explain how to use it to divide angles in increments as small as 1/4 of a deg or 15 minutes.

Never tilt the head of the machine after the spindle has been zeroed square in the "X" & "Y" axes. There are better ways to cut things at an angle.

Keep cutting!

Jim Allen

 

[dwilfong]

"The Brown and sharp is out of my price range."

Don't buy anything made by Brown & Sharp. Buy one of the Chinese copies. With a little tune up time, you can make this work as good as a B & S, especially for what we are doing in our toy motors. The reason a dividing head is preferred; the exact position necessary is determined with a tappered pin in a hole, not by reading a vernier scale. If you decide to use this, I will explain how to use it to divide angles in increments as small as 1/4 of a deg or 15 minutes.

Never tilt the head of the machine after the spindle has been zeroed square in the "X" & "Y" axes. There are better ways to cut things at an angle.

Keep cutting!

Jim Allen

I was looking at Pen tool thy have nice imports at a good price. Bought some things from them before and was very pleased with the quality.

I will wait till I can get a index table before I start cutting the new sleeves.

Have bin carousing Ebay also some times you can get lucky on there. Got my South Bend 9" off ebay for $400 and all the parts for the rebuild. Have less than $1000 in to it when it was all said and done.

I want to make a tool post grinder next. Got any advice on the design.

David

 

[Jim Allen]

"I want to make a tool post grinder next. Got any advice on the design."

My advise is, DO NOT try to make this tool yourself. Look for a used Themac model J-45. You will make a solid mount for the grinder which fastens to the compound of your lathe. Since the grinder's spindle can be rotated around the motor's housing & locked into position, it will be possible to center the grinder's spindle on the lathe's center. You will understand the importance of this when attempting to grind very small holes. This model grinder can run from 4,200 to 42,000 RPM. It can use 1/16" dia grinding pins up to 5" dia grinding wheels. You will be able to grind chromed liners; grind the OD & ID of a hardened steel front end; align grind the holes in any connecting rod; preform cut-off operations with diamond & standard cut off wheels; do face grinding; etc.

I have been told by the owner of this company that when he retires there will be no more Themac grinders produced.

Jim Allen

 

[Michael Costanzo]

Well here it is. just need to get the right bolts for the clamp.

Wow! This is beautiful! Now think what would happen if your fixture could be mounted to a Brown & Sharp, tilting type dividing head. You would be able to accurately cut just about any transfer or exhaust angle simply by using translation & rotation.

Learning to make fixtures is the important key that will allow you to make any part in the motor on a manual machine. Congratulations!

Jim Allen

nice job dave.you have only been in the hobby a short while and have been praised by one of the finest machinist in the hobby.glad to see people diving head first and trying any and everything.mikie.

Thanks mikie. All this practice I will be able to make that 90 RS of yours a real killer eng.

Now get that JAE running right and you will have one killer ride.

David

working on it as we speak.hopefully a few weeks i will out testing. will use the back up motor and find some big boats to play with,we will get this fixed.BEEP,BEEP..my A !

 

[Tom Foley]

Your wife is gonna hate that fixture !!!! :lol:

 

[Ray Sametz]

Incase i'm in the mood of some drooling , i'll go to the Page of Jim ( Allen) and watch the pictures . Its amazing and they are a piece of art in my eyes . And then you read the notes with the pictures , .

I've said this before but thanks Jim for putting those pics online

B

Yup, I too appreciate all the years of information and experience you've put in your gallery Jim.

One of these years I'm gonna get back to re-chroming liners and matching them to high silicone pisons and I already have a lot of ideas from your gallery on how to do it better.

Terry, if done right, the housing will wear out before the liner. I can remember many nights in Brian's basement honing re-chromed sleeves for our OPS motors back in the day. All that was caused Jim showed him how when he lived on the Island. B)

 

[dwilfong]

"The Brown and sharp is out of my price range."

Don't buy anything made by Brown & Sharp. Buy one of the Chinese copies. With a little tune up time, you can make this work as good as a B & S, especially for what we are doing in our toy motors. The reason a dividing head is preferred; the exact position necessary is determined with a tappered pin in a hole, not by reading a vernier scale. If you decide to use this, I will explain how to use it to divide angles in increments as small as 1/4 of a deg or 15 minutes.

Never tilt the head of the machine after the spindle has been zeroed square in the "X" & "Y" axes. There are better ways to cut things at an angle.

Keep cutting!

Jim Allen

Jim I found this I can put a 1 1/2-8 chuck on it to hold the fixture I made. also has a MT2 tapper on the inside to fit a drill chuck I have.

what do you think? It will fit in my small machine real nice and is in the budget.

http://www.ebay.com/...803216481399955

David

 

[Terry Keeley]

Terry, if done right, the housing will wear out before the liner. I can remember many nights in Brian's basement honing re-chromed sleeves for our OPS motors back in the day. All that was caused Jim showed him how when he lived on the Island. B)

Built this grinder about 10 years ago with my toolmaker bud Rudy Pechmann, did about 6 liners and it worked very well.

Want to re-visit it soon, thinking I'll try some very low taper sleeves and 30% Si pistons... h34r:

 

[dwilfong]

At this point I am just looking to mod existing liners. Will be some time before I I try to make my own.

The wife loves my fixture.

She thinks it beautifully. :wub:

Terry that is one great looking unit. Please stop showing it to me.It will just get me wound up.I have enough on my plate right now.

Thats like showing a brick of Bolivian fish scale to a crack addict. :wacko:

David

 

[Ray Sametz]

Terry, if done right, the housing will wear out before the liner. I can remember many nights in Brian's basement honing re-chromed sleeves for our OPS motors back in the day. All that was caused Jim showed him how when he lived on the Island. B)

Built this grinder about 10 years ago with my toolmaker bud Rudy Pechmann, did about 6 liners and it worked very well.

Want to re-visit it soon, thinking I'll try some very low taper sleeves and 30% Si pistons... h34r:

Nice machine Terry, and not a speck of dust on it. :lol: Back in the day the piston was not the problem, the chrome on the liners was the problem when the EPA got involved. Mostly started with the OPS 90 a 3 piece case (total design mistake) liners worn to the brass after 1 season. :blink: Believe it or not, we had 21 KB inboards screaming with new liners only. B)

 

[Joe Warren]

In this eng the numbers are 129 trans and boost 187 ex stock numbers. the chrome is still on the top of the export. thats where all the toque is coming from.

I am going to work on the boost angle and timing first to get a 3deg separation. will angle the boost to hit the center of the pug first then work it twards the back as I test.

Ordered the concave and convex tool bit in a 1/32 radii to do the piston work and make a mirror image in the button.will try the 50% squash and slam it down to .006 will end up at 9.1CR and 69 MSV at 24500RPM with a 1.02cc volume.

Was talking with Dave at the race and he told me he is running over 200ex in his big engines.

Got this mill for 300 with the tooling. could not say no to the deal.

David

David 200 ex timing will get you nothing if you are trying to turn More wheel. The 101 is 187-188 stock exhaust timing What are your intake numbers?

 

[dwilfong]

In this eng the numbers are 129 trans and boost 187 ex stock numbers. the chrome is still on the top of the export. thats where all the toque is coming from.

I am going to work on the boost angle and timing first to get a 3deg separation. will angle the boost to hit the center of the pug first then work it twards the back as I test.

Ordered the concave and convex tool bit in a 1/32 radii to do the piston work and make a mirror image in the button.will try the 50% squash and slam it down to .006 will end up at 9.1CR and 69 MSV at 24500RPM with a 1.02cc volume.

Was talking with Dave at the race and he told me he is running over 200ex in his big engines.

Got this mill for 300 with the tooling. could not say no to the deal.

David

David 200 ex timing will get you nothing if you are trying to turn More wheel. The 101 is 187-188 stock exhaust timing What are your intake numbers?

Disk is open at BDC and close at 65 ATDC. 245 total deg. the trans and boost are 129 the stock numbers.

That what I was thinking way to high but it works for a high rever I guess. I have never gone there nor do I think I will try.

 

[dwilfong]

245 degrees Thats alot of total Induction for a Lugger setup 218 - 220 total closing still @ 65 degrees atdc would be closer to what you want to pull those Uber big Props might aswell cut that exh to 200 and turn some RRRR"s

Have extra disks will try a swap at the pond and log the results. Will start with stock disk and work my way up.David

 

[Jim Allen]

Jim I found this I can put a 1 1/2-8 chuck on it to hold the fixture I made. also has a MT2 tapper on the inside to fit a drill chuck I have.

what do you think? It will fit in my small machine real nice and is in the budget.

http://www.ebay.com/...803216481399955

David

Now you're cooking! All B & S type dividing heads are geared 40 to 1, therefore 40 turns of the handle will equal 360 deg. One turn of the handle will equal 9 deg. If the plate has 18 holes, each movement of one hole equals 1/2 of a deg or 30 minutes. How many holes must the plate have to make each movement of one hole equal to 1/4 of a degree or 15 minutes? Answer, 36 holes. Since there is no 36 hole plate you will add 18 more holes to the 18 hole plate. Use your rotary table to do this because it is marked at least every degree. Learing to use this will allow you to cut very precisely, window widths & heights on any liner whose OD is not greater than roughly 1.500".

I have stated many times previously that a degree wheel & a Dremel can do very little when building or modifing our toy motors. Windows that are mirror images that are not exactly matched will create swirl in the cylinder. This is a HP killer. Learn to cut the liner by using simple trigonometry. All the necessary information is available: the stroke; the connecting rod center distance; the distance from the wrist pin center to the piston crown. For those who cannot do the math, draw the piece up accurately on .100 grid graph paper at a 10 to 1 scale. Use a machinist's scale & magnifier to measure directly from the print using the three numbers from above for any timing you want. Dividing by 10 any measured distance will give great accuracy.

At some latter date I will explain the secret in determining liner taper & piston top taper in a properly fitted motor. Proper fitting is one of the keys to long piston liner life & high HP.

Jim Allen

 

[dwilfong]

Jim I found this I can put a 1 1/2-8 chuck on it to hold the fixture I made. also has a MT2 tapper on the inside to fit a drill chuck I have.

what do you think? It will fit in my small machine real nice and is in the budget.

http://www.ebay.com/...803216481399955

David

Now you're cooking! All B & S type dividing heads are geared 40 to 1, therefore 40 turns of the handle will equal 360 deg. One turn of the handle will equal 9 deg. If the plate has 18 holes, each movement of one hole equals 1/2 of a deg or 30 minutes. How many holes must the plate have to make each movement of one hole equal to 1/4 of a degree or 15 minutes? Answer, 36 holes. Since there is no 36 hole plate you will add 18 more holes to the 18 hole plate. Use your rotary table to do this because it is marked at least every degree. Learing to use this will allow you to cut very precisely, window widths & heights on any liner whose OD is not greater than roughly 1.500".

I have stated many times previously that a degree wheel & a Dremel can do very little when building or modifing our toy motors. Windows that are mirror images that are not exactly matched will create swirl in the cylinder. This is a HP killer. Learn to cut the liner by using simple trigonometry. All the necessary information is available: the stroke; the connecting rod center distance; the distance from the wrist pin center to the piston crown. For those who cannot do the math, draw the piece up accurately on .100 grid graph paper at a 10 to 1 scale. Use a machinist's scale & magnifier to measure directly from the print using the three numbers from above for any timing you want. Dividing by 10 any measured distance will give great accuracy.

At some latter date I will explain the secret in determining liner taper & piston top taper in a properly fitted motor. Proper fitting is one of the keys to long piston liner life & high HP.

Jim Allen

Jim thanks for your input. I will be getting the BS-0 after are club race the Orlando Winter Nat's is completed. much to do to get ready for this race.

working on a new boat design to hopefully run at the race if all the testing works out.

David

 

[dwilfong]

Well got the new wheel from Mark to test this week. 3020-20 cut down to just shy of 68mm. 3deg back cut off the 20. different profile and a small v cut at the hub.

The blade area looks good and the numbers look good 5.5 lead in 6 cob 12.86 cup.

Will post the result of the test when done.

Will see how this one spins.

Come on 100MPH where you at

David

 

[shoboat]

David,

You are going to need aprox. 24,000 RPM to get their Monday.

That propeller is pretty thin, it will not take too much abuse until

it gets hardened. This maybe the one!

Good Luck And Be Safe,

Mark Sholund

 

[aaron alberico]

David,

You are going to need aprox. 24,000 RPM to get their Monday.

That propeller is pretty thin, it will not take too much abuse until

it gets hardened. This maybe the one!

Good Luck And Be Safe,

Mark Sholund

Mark

If the propeller is nice and efficient David will not need near that many rpm's with that prop to go 100mph!

I trimmed one up awhile ago for my SAW 90 rigger, with a little more rpm's then 24000

it was waaaaaayyyyyyyy over 100mph

regards Aaron

 

[dwilfong]

David,

You are going to need aprox. 24,000 RPM to get their Monday.

That propeller is pretty thin, it will not take too much abuse until

it gets hardened. This maybe the one!

Good Luck And Be Safe,

Mark Sholund

Mark

If the propeller is nice and efficient David will not need near that many rpm's with that prop to go 100mph!

I trimmed one up awhile ago for my SAW 90 rigger, with a little more rpm's then 24000

it was waaaaaayyyyyyyy over 100mph

regards Aaron

Dam I hope you are right. will know tomorrow. Just remember this is not a lite on the water SAW boat. This thing is as tight as a 12yr.old virgin.

Then I will have to work on refining the set up to keep it on the water in a 6 boat heat race. :lol:

Have a sheet of .060 titanium just itching to make a wider turn fin.

David

 

[shoboat]

Aaron,

If you look at the on board tach David's RPM is in the

20K to 24K range. It will need to be just about 24K to

get his boat to 100MPH. Your 91 may be revving close

to 30K and that with the weight difference is going to be

the difference. Propeller efficiencies are something that

we are working on a lot lately. Interesting results with

the V-4 Eagletree set up. I don't know how much on

board electric boats you guys work with down under,

But they can teach you a lot about propellers once

you start to figure out what works well on them.

Thanks For The Post,

Happy Holidays To You And Your Family Aaron,

Mark Sholund